At what point do you abandon hope?

An idyllic summer’s day, a children’s birthday party and a simple, innocent game of Hide and Seek.
What should be the happiest of occasions for the Bryson family turns into their worst nightmare as three year old Grace disappears from their own garden, devastating the family and changing their lives forever. But fourteen years later when her sister Elise sees a young woman in a department store she becomes convinced that it is Grace. How can Elise, heavily pregnant with her first child, convince her family and the police that she is not mistaken? Could Grace still be alive and if so, where has she been since disappearing, and what really happened on that summer afternoon fourteen years ago?